Several Japanese laboratories have found that substances in broiled fish and meat and in pyrolysed proteins or certain amino acids are Ames test positive mutagens when activated by rat liver microsomes. In view of the correlation betwen mutagens and carcinogens, it is implied but not demonstrated that these mutagens are probably carcinogens. It is proposed to prepare the pyrolytic product of l tryptophan, Trp-P-2 which on activation is a most powerful mutagen. Its mutagenic action on transforming DNA will be determined and its carcinogenic action in rats. Use of naked transforming DNA, free in solution in place of Ames test bacteria, permits a better evaluation of the structure of the activated mutagen and of the process of mutagenesis. An analysis of the activation reaction and identification of the activated form are planned as well as a study of the bases in DNA with which the activated mutagen reacts. The public health implications of the pyrolysis products are emphasized as well as the need for a thorough study of the problem.